To an increasing degree, motor vehicles are being equipped with navigation devices which make it easier for the driver to reach his/her destination by appropriate indications on a display or by spoken messages. The data necessary for this purpose are generally obtained from a stored road map, a location finder (GPS) or by other sensors such as a map measurer and compass. Electrical power is required to operate these devices, it being possible to obtain this power without difficulty from the vehicle battery which is constantly being recharged during travel. However, extended operation of the navigation device with the engine shut off can result in an undesired drainage of the battery. For that reason, navigation devices are switched off if the motor vehicle is not used for an extended period of time.
However, in order to be able to recover all functions of the navigation device immediately after a short pause, a standby operation is provided in known navigation devices in which the power consumption is in fact limited; however, the most important functions for a fast recovery of operation are preserved.